The present invention relates generally to methods of fabricating stents.
Stents are known in the art. They are typically formed of a cylindrical metal mesh which can expand when pressure is internally applied. Alternatively, they can be formed of wire wrapped into a cylindrical shape.
As described in U.S. Pat. No. 4,776,337 to Palmaz, the cylindrical metal mesh shape is produced by laser cutting a thin walled metal tube. The laser cuts away all but the lines and curves of the mesh.
The method of U.S. Pat. No. ""337 is applicable for relatively large mesh shapes and for meshes whose lines are relatively wide. However, for more delicate and/or intricate shapes, the spot size of the laser is too large.
It is, therefore, an object of the present invention to provide a stent fabrication method which can produce stents with relatively intricate and/or delicate designs.
The method involves first creating a flat version of the desired stent pattern from a piece of thin sheet metal. The flat pattern can be produced through any suitable technique, such as etching the design into the sheet metal, or by cutting with a very fine laser, should one become commercially available or by any other technique.
Once the sheet metal has been cut, it is deformed so as to cause its edges to meet. To create a cylindrical stent from a flat, roughly rectangular metal pattern, the flat metal is rolled until the edges meet. The locations where edges meet are joined together, such as by spot welding. Afterwards, the stent is polished, either mechanically or electrochemically.
It is an object of this invention to provide an apparatus for fabricating a stent, comprising:
a) a platform adapted to receive a flat sheet of metal to be formed into the stent, the flat sheet of metal having a longitudinal axis, a first major surface, a second major surface, a first long side, and a second long side, the first and the second long sides substantially parallel to the longitudinal axis of the sheet;
b) a mandrel having a substantially cylindrical external surface and having a first end and a second end defining a longitudinal axis, the mandrel sized to have a cross-sectional diameter substantially equal to or less than the internal diameter of the stent to be fabricated;
c) means for securing the mandrel against a major surface of the flat sheet of metal; and
d) means for deforming the flat sheet of metal against the external surface of the mandrel so that the flat sheet of metal is deformed into a substantially tubular shape, the means for deforming adapted so that the first long side and the second long side remain substantially parallel to each other when the flat sheet of metal is deformed into the tubular shape.
It is another object of this invention to provide and apparatus for fabricating a stent, comprising:
a) a base having a platform adapted to receive a flat sheet of metal to be formed into the stent, the flat sheet of metal having a longitudinal axis, a first major surface, a second major surface, a first long side, and a second long side, the first and the second long sides substantially parallel to the longitudinal axis of the stent;
b) a mandrel having a substantially cylindrical external surface and having a first end and a second end defining a longitudinal axis, the mandrel sized to have a cross-sectional diameter substantially equal to or less than the internal diameter of the stent to be fabricated;
c) means for securing the mandrel against a major surface of the flat sheet of metal;
d) a plurality of deforming blades disposed around the periphery of the mandrel for deforming the flat sheet of metal against the external surface of the mandrel so that the flat sheet of metal is deformed into a substantially tubular shape, the blades disposed between the first end and the second end of the mandrel, each of the deforming blades adapted for independent and selective movement in a first direction toward the mandrel and a second direction away from the mandrel so as to selectively impinge upon the mandrel or upon a portion of the sheet disposed between the mandrel and each of the deforming blades, each of the deforming blades further adapted so that the first long side and the second long side of the sheet remain substantially parallel to each other when the stent is deformed into the tubular shape;
e) means for selectively moving each of the deforming blades in a first direction toward the mandrel and in a second direction away from the mandrel; and
f) means for securing the first long side of the sheet to the second long side of the sheet.
It is yet another object of this invention to provide an apparatus for fabricating a stent, comprising: means for securing the first long side of the sheet to the second long side of the sheet.
It is still another object of this invention to provide an apparatus for fabricating a stent, comprising:
a) a base;
b) a sheet receiving area disposed on the base, the area adapted to receive a flat sheet of metal to be formed into the stent, the flat sheet of metal having a longitudinal axis, a first major surface, a second major surface, a first long side, and a second long side, the first and the second long sides substantially parallel to the longitudinal axis;
c) an arm having a first end and a second end, the first end of the arm adapted to selectively retain a mandrel having a substantially cylindrical external surface, the second end of the arm hingedly connected to the base and adapted for movement in a first direction toward the base and in a second direction away from the base and further adapted to secure the mandrel against a major surface of the flat sheet of metal disposed on the stent receiving area disposed on the base, the mandrel sized to have a cross-sectional diameter substantially equal to or less than the internal cross-sectional diameter of the stent to be fabricated;
d) means for deforming the flat piece of metal against the external surface of the mandrel so that the flat sheet of metal is deformed into a substantially tubular shape substantially conforming to the external surface of the mandrel with the first long side and the second long side substantially parallel to each other.
It is yet another object of this invention to provide a stent aligning and welding jig comprising:
a) a base having a first end and a second end, a first wall having a first end and a second end and a first major surface and a second major surface; a second wall having a first end and a second end and a first major surface and a second major surface, the second major surface of the first wall and the first major surface of the second wall defining a longitudinal U-shaped channel having a longitudinal axis in the base, the first wall provided with a plurality of slots defining a plurality of first clamping portions having a top end and a bottom end and a first major surface and a second major surface, each of the first clamping portions provided with a first concave channel disposed at the top end of the second major surface of the first clamping portion and a second concave channel disposed at the bottom end of the second major surface of the first clamping portion, the first and the second concave channels substantially parallel to the longitudinal axis of the U-shaped channel; the first wall of each of the plurality of first clamping portions provided with a compensation slit disposed between the first concave channel and the second concave channel, the compensation slit substantially parallel to the longitudinal axis of the U-shaped channel;
b) a plurality of second clamping portions disposed in the U-shaped channel between the second major surface of the first wall and the first major surface of the second wall, each of the second clamping portions disposed in registry with one of the first clamping portions, each of the second clamping portions having a top end, a bottom end, a first major surface, a second major surface, a first minor surface disposed at the top end, a second minor surface disposed at the bottom end, a third minor surface disposed between the top end and the bottom end, and a fourth minor surface disposed opposite the third minor surface between the top end and the bottom end, each of the second clamping portions provided with a first concave channel disposed at the top end of the first major surface of the second clamping portion and a second concave channel disposed at the bottom end of the first major surface of the second clamping portion, the first and the second concave channels substantially parallel to the longitudinal axis of the U-shaped channel;
c) a biasing means disposed between the first major surface of the second wall and the second major surface of each of the plurality of second clamping portions for biasing the first major surface of each of the second clamping portions against the second major surface of each of the first clamping portions which are in registry with each other;
d) a first mandrel support lever positioning pin projecting from the third minor surface and a second mandrel support lever positioning pin projecting from the fourth minor surface of each of the second clamping portions, the mandrel support lever positioning pins substantially parallel to the longitudinal axis of the U-shaped channel;
e) a biasing control means for selectively controlling the distance between the second major surface of each of the first clamping portions and the first major surface of each of the second clamping portions;
f) a retaining mandrel disposed in the second concave channel of the first wall and the second concave channel in each of the second clamping portions; and
g) a mandrel support lever for supporting the stent during the alignment of the first long side of the sheet with the second long side of the sheet, the lever provided with a first mandrel support notch for supporting the first end of the mandrel, a second mandrel support notch for supporting the second end of the mandrel, a first mandrel support lever positioning pin engagement surface for engaging the first mandrel support lever positioning pin and a second mandrel support lever positioning pin engagement surface for engaging the second mandrel support lever positioning pin when the mandrel support lever is disposed on the second wall.
It is still another object of this invention to provide a method of fabricating a stent comprising the steps of:
a) providing a plurality of stent patterns into a flat piece of metal, each of the patterns having a first long side and a second long side, the first long side provided with a plurality of pairs of engagement points, the second long side provided with a plurality of pairs of engagement points, the plurality of pairs of engagement points disposed substantially opposite each other, the engagement points sized and disposed to communicate when the pattern is deformed and rolled into a tubular shape, each pair of the first long side engagement points provided with a bridge disposed between each first long side engagement point comprising the pair, the bridge having a width that is less than the width of the other portions of the stent;
b) disposing a mandrel having a substantially cylindrical external surface and a longitudinal axis between the first long side and the second long side of the sheet, the longitudinal axis substantially parallel to the first long side and the second long side;
c) deforming the pattern into a tubular shape so that the first long side pairs of engagement points contact the second long side pairs of engagement points;
d) cutting the bridge; and
e) attaching each of the engagement points to the engagement point with which it is in contact to form the expandable stent.
It is yet another object of this invention to provide a jig for electropolishing a tubular stent, comprising:
a) a base;
b) an electrically conductive first member having a first end connected to the base and a second end adapted to selectively contact the external surface of the tubular stent without damaging the external surface;
c) an electrically non-conductive second member having a first end connected to the base and a second end adapted to be selectively disposed within the longitudinal bore of the stent without damaging the longitudinal bore, the first member and the second member further adapted so as to bias the second end of the second member towards the second end of the first member in an amount sufficient to secure the stent between the first and the second members.
It is still another object to this invention to provide a method of electropolishing a stent, comprising the steps of:
a) mounting a stent on a rack, the rack having a first end and a second end provided with a plurality of stent electropolishing mounts, each of the mounts having a base; an electrically conductive first member having a first end connected to the base and a second end adapted to selectively contact the external surface of the tubular stent without damaging the external surface; an electrically non-conductive second member having a first end connected to the base and a second end adapted to be selectively disposed within the longitudinal bore of the stent without damaging the longitudinal bore, the first member and the second member further adapted so as to bias the second end of the second member towards the second end of the first member in an amount sufficient to secure the stent between the first and the second members;
b) immersing the stent in an electropolishing bath and applying electrical current to the first member for a predetermined period of time; and
c) changing the point where the second end of the first member contacts the external surface of the stent prior to the expiration of the predetermined period of time.
It is yet another object of this invention to provide a method of fabricating a stent comprising the steps of:
a) providing a plurality of stent patterns in a flat sheet of metal; each of the patterns having a first long side and a second long side, the first long side provided with a plurality of pairs of engagement points, the second long side provided with a plurality of pairs of engagement points, the plurality of pairs of engagement points disposed substantially opposite each other, the engagement points sized and disposed to communicate when the pattern is deformed and rolled into a tubular shape, each pair of the first long side engagement points provided with a bridge disposed between each first long side engagement point comprising the pair, the bridge having a width that is less than the width of the other portions of the stent;
b) disposing a mandrel having a substantially cylindrical external surface and a longitudinal axis between the first long side and the second long side of the sheet, the longitudinal axis substantially parallel to the first and the second long sides;
c) deforming the pattern into a tubular shape so that the first long side pairs of engagement points contact the second long side pairs of engagement points and allowing a portion of the stent to remain attached to the sheet of metal;
d) cutting the bridge;
e) attaching each of the engagement points to the engagement point with which it is in contact to form the stent;
f) attaching an electrode to the sheet of metal;
g) electropolishing the stent; and
f) disconnecting the stent from the sheet.
It is yet another object of this invention to provide a sheet for fabricating a stent having a longitudinal lumen:
a) a flat piece of sheet metal provided with a plurality of stent patterns, each of the patterns having a first long side and a second long side, the first long side provided with a plurality of pairs of engagement points, the second long side provided with a plurality of pairs of engagement points, the plurality of pairs of engagement points disposed substantially opposite each other, the engagement points sized and disposed to communicate when the pattern is deformed and rolled into a tubular shape, each pair of the first long side engagement points provided with a bridge disposed between each first long side engagement point comprising the pair, the bridge having a width that is less than the width of the other portions of the stent.
It is yet another object of this invention to provide a method for fabricating a stent having a longitudinal lumen comprising the steps of:
a.) constructing an apparatus comprising:
a) a laser housing;
b) a laser disposed within and selectively movable within the housing;
c) a movable table having a first end and a second end and adapted for selective movement into and out of the laser housing the table adapted so that when the first end of the table is disposed within the laser housing the second end of the table is disposed outside of the housing and when the second end of the table is disposed within the laser housing the first end of the table is disposed outside of the laser housing;
d) a plurality of stent folders disposed at the first end of the table and a plurality of stent folders disposed at the second end of the table, each of the stent folders comprising:
a) a base having a platform adapted to receive a flat sheet of metal to be formed into the stent, the flat sheet of metal having a longitudinal axis, a first major surface, a second major surface, a first long side, and a second long side, the first and the second long sides substantially parallel to the longitudinal axis, the sheet provided with a plurality of alignment of apertures;
b) a plurality of alignment pins projecting from each of the platforms, the pins sized to engage the alignment apertures and align the sheet on the platform;
c) a mandrel having a substantially cylindrical external surface and having a first end, a second end, and a longitudinal axis, the mandrel sized to have a cross-sectional diameter substantially equal to or less than the internal diameter of the stent to be fabricated, the platform provided with a first concave recess adapted to receive the first end of the mandrel and a second concave recess adapted to receive the second end of the mandrel;
d) a hingedly connected arm adapted for movement in a first direction toward the platform and in a second direction away from the platform for securing the mandrel against a major surface of the flat sheet of metal;
e) a first deforming blade provided with a first deforming blade tip; a second deforming blade provided with a second deforming blade tip; a third deforming blade provided with a third deforming blade tip; a fourth deforming blade provided with a fourth deforming blade tip; a fifth deforming blade provided with a fifth deforming blade tip; and a sixth deforming blade provided with a sixth deforming blade tip, the blades disposed around the external surface of the mandrel, the deforming blade tips adapted to deform the flat sheet of metal against the external surface of the mandrel so that the flat sheet of metal is deformed into a substantially tubular shape substantially conforming to the external surface, the deforming blades disposed between the first end and the second end of the mandrel, each of the deforming blades adapted for independent and selective movement in a first direction toward the mandrel and a second direction away from the mandrel so as to selectively impinge the deforming blade tips against the mandrel or against a portion of the sheet disposed between the mandrel and each of the deforming blade tips, each of the deforming blades further adapted so that the first long side and the second long side of the sheet remain substantially parallel to each other when the stent is deformed into the tubular shape, the third and the sixth deforming blade tips provided with a plurality of scalloped laser apertures, the apertures sized and disposed to permit the third and the sixth deforming blade tips to secure the first long side and the second long side against the external surface of the mandrel while providing the laser access to predetermined portions of the first long side and the second long side of the sheet in order to weld the first long side to the second long side;
f) a first motor connected to the first deforming blade; a second motor connected to the second deforming blade; a third motor connected to the third deforming blade; a fourth motor connected to the fourth deforming blade; a fifth motor connected to the fifth deforming blade; and a sixth motor connected to the sixth deforming blade, each of the motors adapted for selectively moving each of the deforming blades to which it is connected in a first direction toward the mandrel and in a second direction away from the mandrel; and
g) a computer for controlling: the sequence which the first end of the table and the second end of the table are disposed within the laser housing; for controlling the sequence and degree to which each of the plurality of deforming blade tips impinges upon the mandrel or a portion of the sheet disposed between the mandrel and each of the deforming blade tips; and for controlling the sequence, pattern, location, and amount of energy the laser applies to each of the first and the second long sides of each of the sheets disposed on each of the plurality of stent folders;
b.) cutting a plurality of stent patterns into a flat piece of metal, each of the patterns having a first major surface and a second major surface, a first long side and a second long side, the first long side provided with a plurality of pairs of engagement points, the second long side provided with a plurality of pairs of engagement points, the plurality of pairs of engagement points disposed substantially opposite each other, the engagement points sized and disposed to communicate when the pattern is deformed and rolled into a tubular shape, each pair of the first long side engagement points provided with a bridge disposed between each first long side engagement point comprising the pair, the bridge having a width that is less than the width of the other portions of the stent, the sheet provided with a plurality of alignment apertures sized and disposed to engage the alignment pins on the base;
c.) disposing the sheet on the base so that the first major surface of the sheet is in contact with the base;
d.) disposing a mandrel having a substantially cylindrical external surface and a longitudinal axis against the second major surface of the sheet between the first long side and the second long side of the sheet, the longitudinal axis substantially parallel to the first long side and the second long side;
e.) deforming the pattern into a tubular shape so that the first long side pairs of engagement points contact the second long side pairs of engagement points the deforming step comprising the steps of:
a) actuating the sixth deforming blade motor so that the sixth deforming blade motor moves the sixth deforming blade in the first direction in an amount sufficient for the sixth deforming blade tip to contact the external surface of the mandrel so as to secure the mandrel against the sheet;
b) actuating the first deforming blade motor so that the first blade deforming motor moves the first deforming blade in the first direction in an amount sufficient for the first blade deforming tip to contact the first major surface of the sheet and deform the sheet against the external surface of the mandrel;
c) actuating the second deforming blade motor so that the second deforming blade motor moves the second deforming blade in the first direction in an amount sufficient for the second deforming blade tip to contact the first major surface of the sheet and deform the sheet against the external surface of the mandrel;
d) actuating the third deforming blade motor so that the third deforming blade motor moves the second deforming blade in the first direction in an amount sufficient for the third deforming blade tip to contact the first major surface of the sheet and deform the sheet against the external surface of the mandrel while actuating the sixth deforming blade motor so that the sixth deforming blade moves in the second direction away from the mandrel;
e) actuating the fourth deforming blade motor so that the fourth deforming blade motor moves the fourth deforming blade tip in the first direction in an amount sufficient for the fourth deforming blade tip to contact the first major surface of the sheet and deform the sheet against the external surface of the mandrel;
f) actuating the fifth deforming blade motor so that the fifth deforming blade motor moves the fifth deforming blade in the first direction in an amount sufficient for the fifth deforming blade tip to contact the first major surface of the sheet and deform the sheet against the external surface of the mandrel;
g) actuating the sixth deforming blade motor so that the sixth deforming blade motor moves the second deforming blade in the first direction in an amount sufficient for the second deforming blade tip to contact the first major surface of the sheet and deform the sheet against the external surface of the mandrel;
h) simultaneously actuating the third and sixth deforming blade motors so that the third and sixth deforming blade motors move the third and sixth deforming blades in the first direction in an amount sufficient for the third and sixth deforming blade tips to contact the first major surface of the sheet and deform the sheet against the external surface of the mandrel;
d) utilizing the laser in cutting the bridge; and
e) utilizing the laser in welding each of the engagement points to the engagement point with which it is in contact to form the expandable stent.
It is a further object of this invention to provide a stent having a longitudinal lumen, comprising: a first long side and a second long side, the first long side provided with a plurality of pairs of engagement points, the second long side provided with a plurality of pairs of engagement points, the plurality of pairs of first long side engagement points and the plurality of pairs of second long side engagement points disposed substantially apposite each other and connected to each other via a weld, the weld wider than the other portions of the stent.